The effectiveness of ads is highly doubtful in general - especially when you're looking at impressions rather than clicks. And that's before we consider advertising mostly being mostly a zero-sum game.

Advertisers are willing to pay more for privacy-invading ads because they believe they are more effective. If privacy-invading ads were illegal they'd just go back to context-dependent ads like they have been using for the thousands of years before the internet was invented, and after an adjustment period the revenue will just bounce back to where it was before.

Most advertisers know this already. If privacy-invading ads were so effective, why are all the major brands now using influencers to market their products? Why go through the effort of finding a specific Instagram channel which might be a good fit and convincing the operator to enter a brand deal, when you could also just directly pay Instagram for a highly-targeted ad one swipe away?